Pure tone audiometry is the gold standard for hearing assessment. It relies on identifying the threshold of hearing for an individual, generally using tonal sounds generated by instrumentation designed for clinical use by a hearing professional. The instrumentation and accessories for standard hearing tests are generally specialized electro-medical devices for use in a clinical setting. For example, to obtain a valid threshold test and an audiogram report, tests are generally performed in specialized sound-isolated rooms, often referred to as a “sound room,” to reduce noise levels present in the environment generally to that below the threshold of normal hearing. The combined cost of a sound room and clinical instrumentation for standard audiogram testing can easily exceed $20,000.
Performing a hearing assessment is generally not practical for lay consumers to self-administer, particularly in their home or office setting. Even in quiet room environments, noise levels typically exceed the maximum level required for accurately determining the threshold of hearing. Another limitation for self-administration of a hearing test at home is the complexity associated with the test procedure, which can be perplexing and time consuming for a lay person.
Current hearing evaluation methods and associated reports are generally designed for administration and interpretation by hearing professionals, such as an audiologist, an otolaryngologist, a hearing aid dispenser, etc. Standard audiogram results are generally of little value to a lay consumer and generally present irrelevant information pertaining to hearing aid candidacy. The audiogram test report, generally considered the standard form for hearing assessment and hearing aid prescription, is technical and not suitable for interpretation by a potential hearing aid consumer. For example, a standard audiogram report generally presents a person's hearing sensitivity for tonal sounds from −10 to 110 dB, inversely displayed, versus test frequencies from 125 to 8000 Hz. The hearing sensitivity for each frequency may also be tabulated in other audiogram forms. However, since these reports were designed mainly for clinical diagnostics and interpretation by a professional, they are generally not useful for a lay consumer, particularly for indicating hearing aid candidacy. Furthermore, determining the hearing ability in certain ranges, such as −10 to +15 dB HL, is generally not relevant to a person's ability to carry on normal conversations. Another limitation is the irrelevance of audiometric tonal sounds, which generally do not represent real life sounds. Another barrier for self-performed hearing assessment is related to the aforementioned cost, complexity and inaccessibility of standard hearing test instruments.
To circumvent some of the limitations of standard hearing evaluation methods, automated, computer-based hearing evaluation methods have been proposed, including self-administered online tests using personal computers. These tests are often inadequate, however, due to their inaccuracy, often caused by audio characteristics of consumer electronics not meeting the standards of audiometric testing. For example, consumer electronics, such as a sound card, may introduce unacceptable total harmonic distortion (THD), unpredictable frequency response, excessive signal noise, and/or excessive cross-over distortion. The sources of adverse audio characteristics can be attributed to the sound card, the speaker, consumer headphones, cabling, connectors, etc. In addition to the aforementioned obstacles related to audio characteristics, the calibration of acoustic signals emanating from a consumer transducer (a consumer earphone, for example) represents a daunting challenge, preventing accurate hearing evaluation by the lay consumer using a personal computer, or a personal electronic device.
Hearing screening tests offer basic hearing assessment for individuals on the basis of a pass or fail criteria. Generally speaking, these tests are administered by a hearing professional or a nurse, using a portable instrument, which produces a limited set of test stimuli often at a predetermined level between 20 and 40 dB HL depending on the age of the group being tested. These tests generally vary according to the guidelines of the agency, state, and country. Similar to standard audiometric evaluations, tonal and narrow-band noises are generally presented to administer the hearing screening test. One major drawback of current hearing screening methods is the lack of sensitivity and specificity for determining the hearing ability and indicating hearing aid candidacy. As a result, “failed” subjects are generally referred to a hearing professional for further hearing assessment prior to hearing aid candidacy assessment and hearing aid fitting.